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Dueling Beams of Light

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The computer-based color explorations allow millions of colors to be viewed efficiently, but do you really believe it? Make and mix your own beams of colored light to see what happens.

Materials

Two overhead projectors, or two slide projectors, or one of each

If using overhead projectors, two sheets of thick paper or cardboard with cut out slightly smaller than filters If using slide projectors, two slide holders for filters 

Filters

Pack of color filters (at least 6 colors - red, green, blue, yellow, magenta, and cyan) from a distributor of science education materials. You may also order filters from lighting companies that sell colored gels for theater productions – see source of equipment.

Courtesy of Bob Van Milligan who attended the MVH workshop in Portland, Maine during June, 2006.
Color
Rosco Filter
Red
Deep Salmon #42
Green
Standard Green #2004
Blue
Light Sky Blue #67
Yellow
CalColor90 Cyan #4390
Magenta
Light Straw #11
Cyan
Calcolor90 Magenta #4760

Make your own filters using petri dishes, food color, and food dye.

Primary color circles

What To Do

    Darken room

    Turn on both projectors, put filters in place to color each beam, and merge beams.

    Challenge 1: Find two color filters in which the merged beams of filtered light produce yellow.

    Challenge 2: Stack these two colors over one beam of light (turn off second projector) and see what color is produced.

    Challenge 3: Find two color filters in which the merged beams of filtered light produce your favorite color.

    Challenge 4: Find two color filters that produce your favorite color by stacking the filters over one light beam.

Movies created by Marion Tomusiak, 
Museum of Science, Boston:

Movies of mixing colors of light

Movies of stacking filters over one beam of light: